Physical layer protocol data unit format including padding in a high efficiency wireless lan

Abstract

The present invention relates to a Physical layer Protocol Data unit (PPDU) format including a padding. According to one aspect of the present invention, a method for transmitting data to a plurality of stations on a transmission channel by an Access Point in a WLAN may be provided. The transmission channel may be divided into a plurality of subchannels allocated to the plurality of stations. The method may include generating a padding having a length individually for each of one or more subchannels to which paddings are applied among the plurality of subchannels, the length of the padding making transmissions end simultaneously on the plurality of subchannels, and transmitting a PPDU frame including a data unit without the padding or a data unit added with the padding for each of the plurality of subchannels to the plurality of stations on the transmission channel.

What is claimed is: 
     
         1 . A method for transmitting data to a plurality of Stations (STAs) on a transmission channel by an Access Point (AP) in a Wireless Local Area Network (WLAN), the transmission channel being divided into a plurality of subchannels allocated to the plurality of STAs, the method comprising:
 generating a padding individually for one or more subchannels to which paddings are applied among the plurality of subchannels, wherein the padding has a length such that transmissions end simultaneously on the plurality of subchannels; and   transmitting a Physical layer Protocol Data Unit (PPDU) frame including a data unit without the padding or a data unit added with the padding for each of the plurality of subchannels to the plurality of STAs on the transmission channel.   
     
     
         2 . The method according to  claim 1 , wherein the generating the padding comprises:
 determining whether to apply a padding to each of the plurality of subchannels based on a starting time of the data unit and a length of the data unit for each of the plurality of subchannels; and   determining the length of the padding applied individually for the one or more subchannels based on the starting time of the data unit and the length of the data unit for each of the plurality of subchannels.   
     
     
         3 . The method according to  claim 1 , wherein the data unit added with the padding for each of the plurality of subchannels corresponds to an Aggregated MAC Protocol Data Unit (A-MPDU). 
     
     
         4 . The method according to  claim 1 , wherein the padding includes an A-MPDU padding, and the A-MPDU padding corresponds to one or more 4-octet A-MPDU subframes having null data. 
     
     
         5 . The method according to  claim 1 , wherein the padding corresponds to one of a plurality of fragments divided from one A-MPDU subframe. 
     
     
         6 . The method according to  claim 1 , wherein the padding includes one or more of a Medium Access Control (MAC) padding, a Physical (PHY) padding, or an extension padding. 
     
     
         7 . The method according to  claim 6 , wherein the lengths of the one or more of the MAC padding, the PHY padding, and the extension padding are determined individually for the one or more subchannels. 
     
     
         8 . The method according to  claim 7 , wherein the lengths of the one or more of the MAC padding, the PHY padding, or the extension padding are determined to be equal across the one or more subchannels. 
     
     
         9 . The method according to  claim 2 , wherein a starting time of a data unit on one of the plurality of subchannels is identical to starting times of one or more data units on one or more other subchannels among the plurality of subchannels. 
     
     
         10 . The method according to  claim 9 , wherein the starting times of the plurality of data units on the plurality of subchannels are determined based on a length of a High Efficiency-Long Training Field (HE-LTF) field further included in the PPDU frame, and
 wherein a starting time of the HE-LTF field is identical across the plurality of subchannels and an ending time of the HE-LTF field is identical across the plurality of subchannels.   
     
     
         11 . A method for transmitting data to an Access Point (AP) by a Station (STA) in a Wireless Local Area Network (WLAN), the method comprising:
 receiving a trigger frame from the AP, the trigger frame allocating a plurality of subchannels to the STA and one or more other STAs;   when a padding is applied to a subchannel allocated to the STA, generating the padding having a length such that a transmission on the subchannel allocated to the STA and transmissions on one or more other subchannels allocated to the one or more other STAs end simultaneously; and   transmitting a Physical layer Protocol Data Unit (PPDU) frame including a data unit without the padding or a data unit added with the padding to the AP on the subchannel allocated to the STA.   
     
     
         12 . The method according to  claim 11 , wherein the generating the padding comprises:
 determining whether to apply a padding to the subchannel allocated to the STA based on a length of the PPDU frame indicated by the trigger frame, a starting time of the data unit, and a length of the data unit on the subchannel allocated to the STA; and   determining the length of the padding applied to the subchannel allocated to the STA based on the length of the PPDU frame indicated by the trigger frame, the starting time of the data unit, and the length of the data unit on the subchannel allocated to the STA.   
     
     
         13 . The method according to  claim 11 , wherein the data unit added with the padding corresponds to an Aggregated MAC Protocol Data Unit (A-MPDU). 
     
     
         14 . The method according to  claim 11 , wherein the padding includes an A-MPDU padding, and the A-MPDU padding corresponds to one or more 4-octet A-MPDU subframes having null data. 
     
     
         15 . The method according to  claim 11 , wherein the padding corresponds to one of a plurality of fragments divided from one A-MPDU subframe. 
     
     
         16 . The method according to  claim 11 , wherein the padding includes one or more of a Medium Access Control (MAC) padding, a Physical (PHY) padding, or an extension padding. 
     
     
         17 . The method according to  claim 16 , wherein the lengths of the one or more of the MAC padding, the PHY padding, and the extension padding are determined individually for the plurality of subchannels. 
     
     
         18 . The method according to  claim 17 , wherein the lengths of the one or more of the MAC padding, the PHY padding, or the extension padding are determined to be equal across the plurality of subchannels. 
     
     
         19 . The method according to  claim 12 , wherein a starting time of the data unit on the subchannel allocated to the STA is identical to starting times of one or more data units on the one or more other subchannels. 
     
     
         20 . The method according to  claim 19 , wherein the starting times of the plurality of data units on the plurality of subchannels are determined based on a length of a High Efficiency-Long Training Field (HE-LTF) field further included in the PPDU frame, and
 wherein a starting time of the HE-LTF field is identical across the plurality of subchannels and an ending time of the HE-LTF field is identical across the plurality of subchannels.